I have integrated mruby to my autotools project and out-of-tree build worked fine until 3.4.0. The out-of-tree build is building programs without touching source directory, which is checked and enforced by make distcheck (https://www.gnu.org/software/automake/manual/html_node/Checking-the-Distribution.html)

Since 3.4.0, y.tab.c is generated during build. The generator tries to write it under mrbgems/mruby-compiler/core. But make distcheck made the directory read-only to enforce out-of-tree build, resulting EACCES error:

.../mruby/tools/lrama/lib/lrama/command.rb:55:in `initialize': Permission denied @ rb_sysopen - .../mruby/mrbgems/mruby-compiler/core/y.tab.c (Errno::EACCES)

Is there any way to tell mruby build system to write the generated files under different location other than source tree?
I use build_dir variable in build_config.rb. It works for other files, but y.tab.c is not affected by this variable.